Laminated resin material

ABSTRACT

This invention provides a laminated resin material comprising (1) a fiber reinforced thermoplastic resin layer made by a dispersion method, (2) a gas impermeable resin layer on the fiber reinforced thermoplastic resin layer, and (3) an adhesive resin layer having a melt viscosity of not more than 5000 Pa.s under a shear rate of 10 s −1  at 150° C. and not more than 250 Pa.s under a shear rate of 2000 s −1  at 150° C. on the gas impermeable resin layer. Among them, a laminated resin material in which the fiber reinforced thermoplastic resin layer made by the dispersion method is an expansion molded stampable sheet and which has a skin material further on the adhesive resin layer is a material excellent in both of the characteristics of adhesion and rigidity and suitable as automotive interior materials.

TECHNICAL FIELD

This invention concerns a laminated resin material using a fiberreinforced thermoplastic resin made by a dispersion method as asubstrate material which is suitable, for example, to automotiveinterior materials. Particularly, it relates to a laminated resinmaterial in which the fiber reinforced thermoplastic resin is expansionmolded and a skin material is adhered.

BACKGROUND ART

In recent years, weight-reduction in automobiles has been progressed anda demand for the reduction of weight to automotive interior materialshas also been increased.

Referring to an example of a headliner material as one of automotiveinterior materials, fiber reinforced thermoplastic resins made by adispersion method in which inorganic fibers such as glass fibers arefixed as a core material thereof with a thermoplastic resin such aspolyethylene or polypropylene have been used predominantly. This isbecause it has a merit capable of compatibilizing the weight reductionand the strength. As the fiber reinforced thermoplastic resin made bythe dispersion method, it has been known that an expansion moldablestampable sheet is suitable.

The stampable sheet is produced by a dry dispersion method or a wetdispersion method. The stampable sheet by the dry dispersion method isformed by dispersing discontinuous reinforcing fibers and thermoplasticresin fibers or particles in a gas phase to form a non-woven fabric-likeprecipitates (webs), and then heating and pressuring them to solidifyinto a sheet-form. This is disclosed, for example, in JP-A-2-169632. Onthe other hand, the stampable sheet by the wet dispersion method isformed by dispersing discontinuous reinforcing fibers and thermoplasticresin fibers or particles in a liquid medium such as water or bubbles,making non-woven fabric-like precipitates (webs) from liquid dispersionand then heating and pressurizing them to solidify into a sheet-form.This is disclosed, for example, in JP-B-55-9119 or JP-A-60-58227.

The stampable sheet can be shaped easily by heating to a temperaturehigher than the melting point of the thermoplastic resin as a matrix. Inthe stampable sheet, reinforcing fibers are opened to monofilament stateand piled. Accordingly, when the thermoplastic resin of the matrix ismelted, it tends to resume the state of webs before solidification owingto the rigidity of the reinforcing fibers or the like to recover thethickness near the thickness of the web. A molding product with anincreased thickness can be obtained utilizing the nature described aboveby placing a thermally expanded stampable sheet in a die, compressingthe same while adjusting a clearance of the die such that voids are leftafter solidification and cooling in the molding product and then coolingand solidifying the product. Such a molding method is referred to asexpansion molding which is shown, for example, in JP-A-4-331138. Theobtained molding product (hereinafter also referred to as an expandedmolding product) has a three dimensional network structure in whichreinforcing fibers are dispersed in random directions and entangled.This is a porous body in which crosslinked reinforcing fibers aresecured with the thermoplastic resin.

Along with development of such expansion molding products, with a viewpoint of providing further weight reduction and high rigidity, theexpansion molding products have been utilized recently, for example, asthe core material for automotive interior materials. For example, alaminated product obtained by disposing an adhesive layer on one side ofa stampable sheet, laminating a skin material such as a non-woven fabricon the adhesive layer in a state of thermally expanding the stampablesheet, compressing the same to a desired thickness, bonding thestampable sheet with the skin material, integrating and then expansionmolding the same (hereinafter also referred to as an expansion moldedlaminated-product) has been utilized as automotive headliner materials.As apparent from the example of the application use described above, theautomotive interior material using the stampable sheet is required tohave not only high rigidity but also high adhesion strength between thestampable sheet and the skin material. For obtaining high rigidity,there is a method of expansion molding the stampable sheet to increasethe thickness of the interior material. That is, since the rigidity isin proportion with the cube of the thickness, upon expansion molding ofthe stampable sheet (the compression ratio is decreased) when aclearance is increased, the thickness of the interior material isincreased to enhance the rigidity.

However, in a case of increasing the clearance during molding forenhancing the rigidity, since the compression ratio is small, theadhesion pressure is also decreased, so that the adhesion strengthbetween the stampable sheet and the skin material can not always be saidsufficient. On the other hand, when the clearance during molding isdecreased (compression ratio is increased), the adhesion strengthnaturally increases but high rigidity can no more be obtained since thethickness of the interior material is decreased. As described above, therigidity and the adhesion of the skin material are contrary to eachother and it is difficult to obtain an expansion moldedlaminated-product capable of sufficiently satisfying both of them.

In a case of adhering a skin material by way of an adhesive resin to aporous material such as an expansion molded stampable sheet, athermoplastic resin is preferably used for the adhesive resin. It hasbeen known so far that the adhesion with the skin material is improved,that is, adhesion strength is increased more by the use, for example, oflow density polyethylene with lower melt viscosity as the adhesiveresin. As more concrete examples, there are proposed a thermoplasticresin film having a melt flow rate (hereinafter may be simply referredsometimes also as MFR) of 0.5 g/10 min or more (JP-A-7-9632), apolyethylenic resin having MFR of 5.0 to 30.0 g/10 min (JP-A-7-68721), athermoplastic resin film having MFR of 3 g/10 min or more(JP-A-8-164562), a linear low density polyethylene having MFR of 3 g/10min or more (JP-A-2000-15729) and the like. A resin having a higher MFRhas higher fluidity and lower melt viscosity.

However, when the present inventors have examined adhesion between theexpansion molded stampable sheet and the skin material by using a lowdensity polyethylene having an MFR of 15 g/10 min as the adhesive resin,satisfactory adhesion strength could not always be obtained. It shouldbe noted that the adhesive resin used belongs to a thermoplastic resinhaving an MFR of 0.5 g/10 min or more as proposed in JP-A-7-9632described above.

Then, the present inventors have made earnest study on the causedescribed above and, as a result, have found that reduction of the meltviscosity of the adhesive resin at a low shear rate (for example, shearrate: 10 s⁻¹) is important for increasing the adhesion strength with theskin material while increasing the thickness of the expansion moldedlaminated-product as it is (low compression ratio during molding), andhave accomplished this invention.

Generally, the melt viscosity of thermoplastic resin has a shear ratedependency as shown in FIG. 1. That is, under the constant condition forthe temperature, the melt viscosity is higher when the shear rate islower, whereas the melt viscosity is lower in a case where the shearrate is higher. Any of MFR proposed in the prior art described above isa measured value in a high shear rate region usually of 2000 to 10000s⁻¹ of shear rate.

However, the shear rate dependency on the melt viscosity of thethermoplastic resin differs variously depending, for example, on thekind and the molecular weight of the resin. For example, even when themelt viscosity in the high shear rate region is relatively lowercompared with the melt viscosity of other resins, the melt viscosity inthe low shear rate region is not always lowered to a same extent. Asschematically shown in FIG. 1, the melt viscosity between the resins maysometimes be reversed depending on the case. The present inventors havefound that the adhesive strength relative to the skin material can beincreased by the use of a thermoplastic resin having a lower meltviscosity in the low shear rate region. It has been found that therigidity can be maintained as it is and, in addition, the adhesionstrength with the skin material is also improved while maintaining highrigidity by the use of such an adhesive resin, even when the thicknessof the expansion molded laminated-product is increased.

An object of this invention is to provide a laminated resin materialexcellent in the adhesion with a skin material, having high rigidity andreduced in the weight, as well as a precursor thereof.

DISCLOSURE OF THE INVENTION

This invention provides a laminated resin material comprising: (1) afiber reinforced thermoplastic resin layer made by a dispersion method,(2) a gas impermeable resin layer on the fiber reinforced thermoplasticresin layer, and (3) an adhesive resin layer having a melt viscosity ofnot more than 5000 Pa.s under a shear rate of 10 s⁻¹ at 150° C. and notmore than 250 Pa.s under a shear rate of 2000 s⁻¹ at 150° C. on the gasimpermeable resin layer.

In the laminated resin material, the fiber reinforced thermoplasticresin layer made by the dispersion method described above is preferablyone of members selected from the group consisting of stampable sheetsand webs thereof.

Further, any of the laminated resin layers preferably includes those inwhich the fiber reinforced thermoplastic resin layer made by thedispersion method is an expansion molded stampable sheet, and whichfurther has a skin material on the adhesive resin layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing an example of a relation between ashear rate and a melt viscosity.

FIG. 2 is a cross sectional view showing the outline of a laminatedresin material according to this invention in a case of using astampable sheet as a fiber reinforced thermoplastic resin layer made bydispersion method.

FIG. 3 is a cross sectional view showing the outline of a laminatedresin material (expansion molded laminated-product) according to thisinvention in a case where a skin material is adhered on the adhesiveresin layer.

BEST MODE FOR PRACTICING THE INVENTION

One of the embodiments according to this invention is a laminated resinmaterial comprising: (1) a fiber reinforced thermoplastic resin layermade by a dispersion method, (2) a gas impermeable resin layer on thefiber reinforced thermoplastic resin layer, and (3) an adhesive resinlayer having a melt viscosity of not more than 5000 Pa.s under a shearrate of 10 s⁻¹ at 150° C. and not more than 250 Pa.s under a shear rateof 2000 s⁻¹ at 150° C. on the gas impermeable resin layer.

In the laminated resin material, the fiber reinforced thermoplasticresin layer made by the dispersion method described above preferablyincludes one of members selected from the group consisting of stampablesheets and webs to be used for the stampable sheet. Further, in thelaminated resin material according to this invention, the gasimpermeable resin layer and the adhesive resin layer may be formed on atleast one surface of the fiber reinforced thermoplastic resin layer madeby the dispersion method as a substrate material. Such laminated resinmaterial can be utilized as automotive interior materials, for example,by adhering a skin on the adhesive resin layer. As will be describedlater, those formed by expansion molding of the fiber reinforcedthermoplastic resin layer made by the dispersion method can be usedsuitably as the interior material.

FIG. 2 schematically shows the laminated resin material according tothis invention in a case of using a stampable sheet as the fiberreinforced thermoplastic resin layer made by the dispersion method as anexample. That is, the laminated resin material 1 is a laminate having agas impermeable resin layer 3 on the surface of a stampable sheet 2, andan adhesive resin layer 4 having a predetermined melt viscosity formedon the gas impermeable resin layer 3.

(Fiber Reinforced Thermoplastic Resin Layer Made by Dispersion Method)

The fiber reinforced thermoplastic resin layer made by the dispersionmethod according to this invention comprises dispersed or precipitatedreinforcing fibers secured with thermoplastic resin fibers and isprepared without melting and kneading the reinforcing fibers and thethermoplastic resin. For example, it can include a resin impregnatedsheet formed by impregnating a thermoplastic resin to a laminate ofreinforcing fibers, those formed by laminating or weaving reinforcingfibers deposited with a thermoplastic resin and then fusing or bodingthem, a resin-impregnated glass board, and the stampable sheets, webs tobe used for the stampable sheets described above and, further, resinfoams having open cells incorporating or laminating reinforcing fibers.The resin foams can include, for example, foams of thermoplastic resinssuch as polyethylene, polystyrene and polypropylene. As the fiberreinforced thermoplastic resin made by the dispersion method, stampablesheets or webs to be used for the stampable sheets corresponding to theprecursors thereof are preferred. The feature of the fiber reinforcedthermoplastic resin made by the dispersion method according to thisinvention resides in that the length of the fibers contained is longercompared with that of the fibers of fiber reinforced thermoplasticresins formed by melting and kneading the reinforcing fibers which havebeen referred to long since as “FRP” and the thermoplastic resin.Referring to the stampable sheet as an example those, more typically,having an average length of about 5 to 30 mm and an aspect ratio ofabout 100 or more for the reinforcing fibers contained can be mentionedas preferred examples. In this invention, a thermosetting resin may alsobe mixed with the thermoplastic resin. Further, a thermosetting resincan also be used instead of the thermoplastic resin.

The stampable sheet suitable as a fiber reinforced thermoplastic resinlayer made by the dispersion method according to this invention is asheet obtained by heating the non-woven fabric-like web prepared by thedry method or the wet method as described above and then cooling thesame under pressure. The blending ratio between the reinforcing fiberand the thermoplastic resin is preferably 20/80 to 70/30, particularly,30/70 to 60/40 by mass ratio since an expansion molding product of highmechanical strength such as flexural strength and flexural modulus canbe obtained. The stampable sheet may be incorporated, for example, withadditives such as antioxidant, light fast stabilizer, metal inactivator,flame retardant, carbon black and colorant.

The thermoplastic resin as the main ingredient of the stampable sheetalso has a function of fixing strands or intersections between each ofreinforcing fibers. Such resin can include, for example, polyolefin suchas polyethylene and polypropylene, polystyrene, polyvinyl chloride,polyethylene terephthalate, polycarbonate, polyamide and polyacetal.Further, copolymers such as ethylene—vinyl chloride copolymer,ethylene—vinyl acetate copolymer, styrene—butadiene—acrylonitrilecopolymer, or thermoplastic elastomers based, for example, on EPM orEPDM may be used alone or as a combination of two or more of them. Sincepolyolefin such as polyethylene or polypropylene has excellent strength,rigidity and moldability, it is preferred and, particularly,polypropylene with good balance for such three characteristics and of areduced cost is preferred. Among them, a polypropylene having MFR[measuring conditions: according to JIS K6758, 210° C., 21.18 N (2.16kgf)] of 1 to 200 g/10 min is preferred. With a view point of improvingthe strength of the stampable sheet, it is preferred to usethermoplastic resins applied with modification treatment such as graftmodification with a compound, for example, an acid such as anunsaturated carboxylic acid (maleic acid, acrylic acid or the like), anunsaturated carboxylic acid anhydride (maleic anhydride or the like), orepoxy compounds in combination in order to improve adhesiveness ofreinforcing fibers and thermoplastic resin.

Reinforcing fibers as another main ingredient constituting the stampablesheet may be any of inorganic fibers or organic fibers, or compositefibers of them. The inorganic fibers can include, for example, glassfibers, carbon fibers, boron fibers, stainless steel fibers and othermetal fibers. The organic fibers can include, for example, alamidefibers, polyester fibers, polyamide fibers and wooden fibers. They maybe used alone or as a combination of two or more of them. Among all,glass fibers capable of providing high reinforcing effect at a reducedcost are particularly preferred. The fiber length of the reinforcingfibers is preferably from5 to 30 mm, further preferably, from 10 to 26mm with a view point of ensuring the reinforcing effect, theexpandability and the shaping property. The diameter of the reinforcingfibers is preferably from 5 to 30 μm and, further preferably from 10 to25 μm in order to ensure the reinforcing effect and the expandability.Further, for improving the wetability and the bondability between thereinforcing fibers and the thermoplastic resin, reinforcing fibersapplied with a surface treatment such as with silane coupling agent arepreferred.

(Gas Impermeable Resin Layer)

The gas impermeable resin layer has a function of ensuring the gasimpermeability of the fiber reinforced thermoplastic resin layer made bythe dispersion method or the expansion molding product thereof, andpreventing the adhesive resin laminated on the gas impermeable resinlayer from impregnating into the fiber reinforced thermoplastic resinlayer or the expansion molding product thereof described above as thesubstrate. For example, in a case of application use for the headlinermaterial of automobiles, it can also prevent passage of air therebypreventing the headliner material from contamination. The thickness ofthe gas impermeable resin layer is preferably 5 μm or more and, morepreferably, 10-50 μm in order to maintain the gas impermeability.Further, the gas impermeability can be measured, for example, by themethod according to ASTM-D 737 and those of substantially 0 cm³/cm²·sare used in this invention.

The gas impermeable resin layer may be either a thermoplastic resin or athermosetting resin but the thermoplastic resin is preferred in view ofthe moldability. That is, for example, at least one member selected fromthe group consisting of polyamide, polyethylene terephthalate, andethylene-vinyl alcohol copolymer is preferred. For the gas impermeableresin layer, those resins identical with the thermoplastic resin used asthe main ingredient of the stampable sheet can be used. More preferredare stampable sheets or expansion molded products thereof not melted ata molding temperature thereof. In other words, those of a melting pointhigher than the melting point of the thermoplastic resin as the mainingredient of the stampable sheet are preferred. For example, in a casewhere the matrix resin for the stampable sheet is polypropylene, the gasimpermeable resin layer is preferably constituted, for example, with apolyamide or polyethylene terephthalate.

Since adhesion between the fiber reinforced thermoplastic resin layermade by the dispersion method and the gas impermeable resin layerincludes adhesion also by so-called self adhesion, thermo fusion oradhesion with anchoring in this invention, adhesives are not alwaysrequired. However, in order to improve the workability or the adhesionstrength, use of the adhesives is preferred. In such a case, the gasimpermeable resin layer 3 is bonded by way of the adhesive 5 to thestampable sheet 2 and the adhesive resin layer 4 as the constituentfactor of this invention is formed on the gas impermeable resin layer 3to obtain a laminate. In this case, the adhesive 5 is sometimes observedas a layer. The adhesive 5 is preferably a resin identical or similarwith the matrix resin constituting the fiber reinforced thermoplasticresin made by the dispersion method. “Similar” means copolymer,composition or graft-modified product to the homopolymer. Particularly,in a case of using polypropylene as the matrix resin for the fiberreinforced thermoplastic resin made by the dispersion method, use of apolyolefin is preferred in view of the adhesion to the polypropylene.Polypropylene is further preferred and an acid-modified polypropylene isfurther more preferred. Further, the same adhesive as the adhesive resinlayer to be described later can also be used.

(Adhesive Resin Layer)

The adhesive resin layer of the laminated resin material according tothis invention is formed for adhering the skin material thereon suchthat the gas impermeable resin layer described above and the skinmaterial are not peeled.

The resin constituting the adhesive resin layer in this invention is athermoplastic resin having a melt viscosity of not more than 5000 Pa.sunder a shear rate of 10 s⁻¹ at 150° C. and a melt viscosity of not morethan 250 Pa.s under a shear rate of 2000 s⁻¹ at 150° C. More preferredare thermoplastic resins having a melt viscosity of 80 to 4000 Pa.sunder a shear rate of 10 s⁻¹ at 150° C. and 5 to 240 Pa.s under a shearrate of 2000 s⁻¹ at 150° C.

The temperature upon measuring the melt viscosity is defined as 150° C.,because the temperature of the adhesive resin upon expansion molding islowered to about 150° C. Further, when the melt viscosity is not morethan 5000 Pa.s at a shear rate of 10 s⁻¹ and a melt viscosity is notmore than 250 Pa.s at a shear rate of 2000 s⁻¹, the skin material tendsto intrude easily into the adhesive resin layer to develop an anchoringeffect and improve the adhesion strength with the skin material.

The resin of the adhesive resin layer in this invention has an MFR,preferably, of not less than 8 g/10 min and, more preferably, 8 to 250g/10 min. When MFR is not less than 8 g/10 min, the fluidity of theadhesive resin is favorable and it is bonded easily with the skinmaterial.

Usually, the thickness of the adhesive resin layer in this invention is,preferably, not less than 10 μm and, more preferably, 30 to 100 μm.

There is no particular restriction on the kind of the thermoplasticresin in the adhesive resin layer. It can include, for example, lowdensity polyethylene, medium density polyethylene, high densitypolyethylene, linear low density polyethylene, ethylene vinyl acetatecopolymer, ethylene ethyl acrylate copolymer, ethylene acrylic acidcopolymer, ethylene methyl acrylate copolymer, ethylene methylmethacrylate copolymer, ethylene—methacrylic acid copolymer or a mixturethereof. For example, polyethylenes of different melt viscosity canproperly be combined and used. Polyolefinic resins such as polyethyleneand polypropylene are preferred and, among them, it is preferably atleast one member selected from the group consisting of linear lowdensity polyethylene, low density polyethylene and polypropylene.Polyethylene is particularly preferred since it has low melting pointand is available at a reduced cost.

The melting point of the resin in the adhesive resin layer in thisinvention is preferably 90 to 140° C. When the melting point is notlower than 90° C., adhesion with the skin material can be maintainedeven at a high temperature, and the adhesive resin is less solidifiedduring compression molding under cooling at 140° C. or lower, so thatanchoring effect can be developed easily.

In the case of using several kinds of thermoplastic resins of differentmelt viscosities in admixture as the adhesive resin, since it isdifficult to form a thermoplastic resin with a low melt viscosity at ashear rate of 10 s⁻¹ or 2000 s⁻¹ singly into a film, a thermoplasticresin of higher melt viscosity at a shear rate of 10 s⁻¹ or 2000 s⁻¹ ispreferably mixed to control the melt viscosity of the mixed resin to notmore than 5000 Pa.s at a shear rate of 10 s⁻¹ and to not more than 250Pa.s at a shear rate of 2000 s⁻¹. There is no particular restriction onthe mixing method of the adhesive resin. They may be kneaded uponforming the resin into the film and may be copolymerized or dry blended.Upon mixing, the melt viscosity of one of the thermoplastic resins ismore than 5000 Pa.s at a shear rate of 10 s⁻¹ and more than 250 Pa.s ata shear rate of 2000 s⁻¹.

In this invention, an intermediate layer comprising a resin may furtherbe interposed between the gas impermeable resin layer and the adhesiveresin layer for enhancing adhesion between both of the layers,conforming the adhesion or melting both of the layers to control thefluidity.

(Laminated Resin Material Using Expansion Molded Stampable Sheet as aSubstrate)

Another important feature of this invention resides in any one of thelaminated resin materials described above in which the fiber reinforcedthermoplastic resin layer made by the dispersion method is an expansionmolded stampable sheet, and a laminated resin material further having askin material on the adhesive resin layer. Recently, such laminatedresin layers (also referred to as expansion molded laminated-products)have been used suitably to automotive interior materials. FIG. 3schematically shows an expansion molded laminated-product 6. That is,the laminated resin material 6 has a gas impermeable resin layer 3described above on a expansion molded stampable sheet 8, and a skinmaterial 7 bonded by way of the adhesive resin layer 4 described aboveon the gas impermeable resin layer 3. FIG. 3 shows an example of usingthe same adhesive 5 as described above between the expansion moldedstampable sheet 8 and the gas impermeable resin layer 3. Since the fiberreinforced thermoplastic resin by the dispersion method is the expansionmolded stampable sheet, it is porous in which intersections of thereinforcing fibers are bonded with the thermoplastic resin, so that itis reduced in the weight and excellent in the mechanical properties suchas rigidity.

(Skin Material)

The skin material in this invention has an aim for decoration andprotection. As the skin material, woven fabrics or non-woven fabricscomprising natural fibers such as plant fibers and animal fibers orsynthetic fibers such as cellulose acetate series, polyamide series,polyester series, polyacryl series and polypropylene series fibers arepreferred. Non-woven fabrics of thermoplastic resin are more preferred.Skin materials using the fibers are preferred since the anchoring effectthat the adhesive resin layer is melted and intrudes between each of thefibers of the skin material is large to enhance the adhesion. However,so long as adhesion with the adhesive resin layer is obtained, it is notrestricted to the skin material using the fibers. For example, when afoamed sheet having open cells such as polyurethane foams is disposed tothe surface to be adhering with the core material of the woven fabric ornon-woven fabric, it is possible to absorb unevenness of the corematerial, enhance the aesthetic property of the skin material surfaceand can provide cushioning property.

(Preparation Method for Laminated Resin Material)

The laminated resin material is prepared, for example, by the followingmethod. This example shows, at first, a case in which the fiberreinforced thermoplastic resin layer made by the dispersion method is astampable sheet or a web to be used for stampable sheet.

A thermoplastic resin and reinforcing fibers are dispersed in an aqueoussolution containing a surfactant in which fine air bubbles aredispersed. Solid contents in the liquid dispersion are precipitated bydewatering the obtained liquid dispersion through a porous support.Then, the precipitates are dried to obtain a uniform web. The webcomprises, for example, a thermoplastic resin and reinforcing fibers inwhich particles of the thermoplastic resin are uniformly dispersed inthe reinforcing fibers, and the thickness thereof is about 1 to 10 mm.

Then, a multi-layered film obtained by laminating an adhesive with theweb, a gas impermeable resin and an adhesive resin in this order islaminated to the web such that the adhesive resin layer is on the outersurface. The laminate is melted by heating to a melting point or higherof the thermoplastic resin in the web and pressurized by a cooling plateand solidified into a sheet form, to obtain a dense laminated resinmaterial. By the processing, the web is formed into a materialequivalent with the so-called stampable sheet. When the thermoplasticresin used is polypropylene, the heating temperature is about 170 to230° C., more preferably, about 190 to 210° C. Not more than 230° C. ispreferred since coloration or lowering of the strength by thedecomposition of polypropylene can be suppressed. The pressure by thecooling plate is preferably 0.01 to 5 MPa in order to obtain a denselaminated resin material. Rupture of the reinforcing fibers can besuppressed easily at 5 MPa or less.

Further, the laminated resin material can be prepared also by heatingand then pressurizing under cooling the web described above to onceprepare a stampable sheet and heating the stampable sheet again,laminating the multi-layered film described above and pressurizing andcooling them. The multi-layered film described above comprising theadhesive, the gas impermeable resin and the adhesive resin is preparedby a known production method such as a dry lamination method or aco-extrusion method.

Then, a laminated resin material in which the fiber reinforcedthermoplastic resin layer made by the dispersion method is the expansionmolded stampable sheet and which has a skin material further on theadhesive resin layer is to be exemplified successively.

The laminated resin material obtained in the example described above isre-heated and expanded at a temperature of the melting point of thematrix resin or higher. Then, after laminating the skin material on theexpanded stampable sheet, they are placed in a molding die.Successively, they are pressure molded integrally while controlling theheight of the die spacer and the clamping height of the press die toobtain a laminated resin material (expansion molded laminated-product)having a predetermined thickness. The heating temperature upon expansionmolding is about 170 to 230° C. and, preferably, about 190 to 210° C. ina case where the matrix material is polypropylene. The heating methodincludes a hot plate heating, infrared heating, near infrared heating orblow heating with no particular restriction. The die temperature may benot higher than coagulation point of the thermoplastic resin and usuallyit is from room temperature to about 60° C. with a view point ofhandlability and productivity. While different depending on the shape ofthe molding product, a preferred molding pressure is usually from 0.01to 5 MPa.

EXAMPLE Example 1

Polypropylene particles and glass fibers described below were mixed at50:50 dry mass % ratio in a foamed liquid and dispersed. Then, thefoamed liquid was filtered under suction and dried to obtain a web witha basis weight of 700 g/m² (a kind of fiber reinforced thermoplasticresin layer made by dispersion method) Polypropylene: MFR 65 g/10 min,melting point 162° C. Glass fiber: 25 mm length, 17 μm diameter

Then, a multi-layered film formed by separately laminating polypropylene(melting point 160° C., 40 μm thickness) as an adhesive, 6-nylon(melting point 215° C., 25 μm thickness, gas impermeability : 0cm³/cm²·s) as a gas impermeable resin thereon and an adhesive resin ofthe constitution shown in Table 1 further on the gas impermeable resin,is laminated on one surface of the obtained web to form a laminatedresin material. The laminated resin material was laminated such that theadhesive resin layer of the constitution shown in Table 1 was formed asan outer layer. Further, the laminated resin material having the web asthe substrate was heated to 210° C., then placed on a cooling plate at25° C., and compression molded under pressure of 0.3 MPa into astampable sheet in which polypropylene and reinforcing fibers wereintegrally solidified densely and, at the same time, the multi-layeredfilm was adhered firmly on one side of the stampable sheet to obtain alaminated resin material (refer to FIG. 2).

Further, the laminated resin material having the thus obtained stampablesheet as the substrate was heated to 210° C., the polyester non-wovenfabric described below was laminated as the skin material on theadhesive resin layer and placed in an expansion molding die(temperature:room temperature). Then, a flat plate-like laminated resinmaterial in which the stampable sheet was expansion molded, and the skinmaterial was firmly adhered was obtained (expansion moldedlaminated-product) by closing the die at a pressure of 0.02 MPa (referto FIG. 3). The thickness of the expansion molded stampable sheetportion was 3.3 mm. Polyester non-woven fabric: Basis weight 180 g/m²,with no hot melt layer

For the obtained expansion molded laminated-product, the followingbending test, peeling strength of the skin material at a normaltemperature and hot adhesion retainability test in a high temperatureatmosphere were conducted. The results of the test are shown in Table 2.

(Bending Test)

A test specimen of 150 mm length and 50 mm width was cut out from anexpansion molded laminated-product. Using the test piece, a 3-pointbending test of applying a load on the side of the skin material at 100mm spun and at 50 mm/min cross head speed was conducted and the maximumload and the elasticity gradient were measured. The measuringtemperature was 23° C.

(Peeling Strength for Skin Material)

A test specimen of 150 mm length and 25 mm width was cut out from anexpansion molded laminated-product. The skin material was peeledpartially from the end of the test piece for 50 mm length. Then, thepeeled skin portion and the peeled main body portion were grippedrespectively by chucks and pulled in the direction of 180° to conduct apeeling test. The measuring temperature was 23° C. and the pulling ratewas 50 mm/min.

(Hot Adhesion Retainability Test)

A test specimen of 150 mm length and 25 mm width was cut out from anexpansion molding laminationed-product. Then, the skin material waspartially the peeled from the end of the test piece for 75 mm length.Then, peeled main body portion was gripped, a constant weight of 100 gwas applied to the peeled skin portion and left in an atmosphere at 85°C. The peeling state for the skin material after 24 hours was visuallyobserved.

(MFR)

MFR was measured according to JIS K6758.

(Melt Viscosity)

Melt viscosity was measured by using a flow tester while varying theload.

Examples 2-9, Comparative Examples 1-7

Laminated resin materials (plate-like expansion moldedlaminated-products) were prepared in the same method as in Example 1except for using multi-layered films in which the adhesive resin (A) wasreplaced with adhesive resins B-J shown in Table 1 in Example 1. Theresults for the performance test of the obtained expansion moldedlaminated-products are shown together with the thickness of theexpansion molded stampable sheet portion in Table 2.

It can be seen from the results in Table 2 that the bendingcharacteristic is excellent and the balance of adhesion strengthrelative to the skin material at normal temperature and high temperatureis favorable in the case of using the thermoplastic resin having a meltviscosity of not more than 5000 Pa.s under a shear rate of 10 s⁻¹ at150° C. and not more than 250 Pa.s under a shear rate of 2000 sa⁻¹ at150° C. as an adhesive resin layer. Further, the gas impermeability ofthe expansion molded laminated-products obtained in all of examples andcomparative examples were 0 cm³/cm²·s and they were gas impermeable.

Further, the feeling of the skin material in the ion moldedlaminated-product according to this ion was substantially identical withthe state before on.

TABLE 1 Melt viscosity (Pa.s) Under a Under a Layer Adhesive resin shearrate shear rate MFR thick- Kind and of 10 s⁻¹ of 2000 s⁻¹ (g/ nessSymbol blending ratio at 150° C. at 150° C. 10 min) (μm) A LDPE 120 40200 50 B LLDPE 1900 230 11 50 C LDPE (MFR:7)/ 1100 82 75 50 LDPE (MFR:200) = 1/1 D LDPE (MFR:50)/ 350 95 50 60 LLDPE (MFR: 50) = 1/1 E LDPE(MFR:50)/ 1300 145 20 60 EVA (MFR: 4) = 7/3 F LDPE (MFR:200)/ 2100 13140 60 acrylic acid modified PE (MFR:8) = 4/6 G LDPE 10000 150 15 50 HHDPE 15200 300 4 80 I Acrylic acid 11450 280 8 60 modified PE J LLDPE8200 300 4 60 LDPE : Low density polyethylene LLDPE : Linear low densitypolyethylene HDPE : High density polyethylene

TABLE 2 Adhesiveness of Thickness of Maximum skin material expansionmolded bending Elasticity Peeling strength Adhesive stampable sheet loadgradient at 25° C. Hot resin (mm) (N) (N/mm) (N/25 mm) adhesion* Example1 A 3.3 25.5 3.7 17.6 ◯ 2 B 3.0 24.5 3.1 7.8 ◯ 3 C 3.0 24.5 3.3 11.8 ◯ 4C 3.5 24.5 4.0 6.9 ◯ 5 D 2.8 22.6 3.1 12.7 ◯ 6 D 3.0 26.5 3.3 8.8 ◯ 7 D3.3 25.5 3.5 6.9 ◯ 8 E 2.8 21.6 2.8 7.8 ◯ 9 F 3.0 23.5 3.1 8.8 ◯ Comp.Ex. 1 G 3.0 24.0 3.2 1.1 X 2 H 3.0 24.5 3.3 0.5 X 3 I 3.0 23.5 3.0 2.0 X4 J 1.5 7.8 1.2 15.7 ◯ 5 J 2.0 14.7 2.0 6.9 ◯ 6 J 2.5 17.7 2.5 1.0 X 7 J3.0 23.8 3.0 0.5 X *◯: notpeeled X: partially or entirely peeled

Industrial Applicability

The laminated resin material according to this invention is reduced inweight and has high rigidity and adhesion strength. Particularly, anexpansion molded laminated-product has an excellent balance for rigidityand adhesion with a skin material. Accordingly, it can be appliedeffectively, for example, to automotive interior materials required forreduced weight and high rigidity, for example, headliner materials ordoor trim materials.

What is claimed is:
 1. A laminated resin material comprising: (1) afiber reinforced thermoplastic resin layer made by a dispersion method,(2) a gas impermeable resin layer on the fiber reinforced thermoplasticresin layer, and (3) an adhesive resin layer having a melt viscosity ofnot more than 5000 Pa.s under a shear rate of 10 s⁻¹ at 150° C. and notmore than 250 Pa.s under a shear rate of 2000 s⁻¹ at 150° C. on the gasimpermeable resin layer.
 2. The laminated resin material as defined inclaim 1, wherein the fiber reinforced thermoplastic resin layer made bythe dispersion method is one of members selected from the groupconsisting of stampable sheets and webs to be used for the stampablesheets.
 3. The laminated resin material as defined in claim 1, whereinthe fiber reinforced thermoplastic resin layer made by the dispersionmethod is an expansion molded stampable sheet and the material furtherhas a skin material on the adhesive resin layer.